The table structure is essentially the same. You define a join table to bridge the gap between Suppliers and SupplierContacts.
Suppliers::SupplierID = SupplierContactsXref::SupplierID
SupplierContacts::SupplierContactID = SupplierContactsXref::SupplierContactID
You just have to set this up visually in Manage | Database | Relationships instead of in a SQL Join expression.
Using the above relationship, you can place a portal to SupplierContactsXref on a suppliers based layout and use it to show each supplier contact and you can add fields from supplier contacts to this portal. You can do the opposite if you place a portal to SupplierContactsXref on a SupplierContacts based layout.
Here's a demo that links "Companies" to "Contracts" in this manner: http://www.4shared.com/file/PLhjErzu/Contracts_to_Companies.html